366 



ZOOLOGY 



Adaptations before there were any whales or bats, swimming and 

 flying mammalia, the reptiles had developed similar 



for swim- 

 ing and 

 flying 



Giant rep- 

 tiles of the 

 Mesozoic 

 age 



From Zitlel's " Palaonlologie " 



FIG. 143. Skeleton and body outline of a plesiosaur, restored by R. Owen. 



Jurassic of Dorsetshire, England. 



types. The plesiosaurs were aquatic and had long 

 paddles for swimming, in place of legs. As with the 

 whales, the bony framework of these structures shows 

 plainly that they are derived from legs, and not directly 

 from fishlike fins. The pterosaurs, on the other hand, 

 had long wings and were capable of flight ; yet they 

 were entirely different from birds or bats. One of these 

 creatures, found fossil in Kansas, had a spread of wings 

 measuring nearly 20 feet. It must have been curiously 

 like an airplane. In spite of their wonderful adaptive 

 features, all these animals died out ; indeed, we may say 

 that they disappeared because of their adaptive features, 

 - they were specialized for particular modes of life, and 

 when conditions changed, they could not change to meet 

 them. 



5. The dinosaurs (the name means : ' terrible rep- 

 tiles") were the gigantic reptiles of the Mesozoic; they 

 flourished for about nine million years, and then became 

 extinct. The disappearance of these great, stupid 

 beasts coincides approximately with the rise of the more 

 modern type of mammals, warm-blooded, active, and 

 relatively large-brained. Many dinosaurs were herbiv- 

 orous, feeding on vegetation, and some of these were 



